Process for reduction of high sulfur residue

ABSTRACT

A process for disposing of high sulfur-containing residual oil is disclosed wherein a high sulfur vacuum residual oil is hydrocracked and hydrodesulfurized in an upflow, high pressure, high temperature, ebullated bed reactor, the effluent fractionated, and the 975*F. fraction further subjected to separation by solvent extraction. The extract consists of gas oils, while the raffinate, containing most of the remaining sulfur, is partially oxidized to yield hydrogen which is recycled to the hydrocracking reactor. The heavy gas oil fraction from the extract may also be recycled to extinction in the hydrocracker.

" United States atent [1 1 Gregoli et a].

[54] PROCESS FOR REDUCTION OF HIGH 3,380,912 4/1968 Paterson 208/86 SULFUR RESIDUE 3,434,966 3/1969 Oldenburg 208/309 3,549,517 12/1970 Lehman et a1 208/108 [75] Inventors: Armand A. Gregoii, Somerv1lle,

George Harms Paoh Primary Examiner-Herbert Levine [73] Assignee: Cities Service Research & Attorney, Agent, or Firm-George L. Rushton Development Co., Cranbury, NJ.

[22] Filed: Aug. 115, 11973 57 S C PP N04 388,531 A process for disposing of high sulfur-containing resid- Related Us. Applicaflon Data ual oil is disclosed wherein a high sulfur vacuum resid- Co ti mi in an of Scr NO 230 910 March I ual oil is hydrocracked and hydrodesulfurized in an g g upflow, high pressure, high temperature, ebullated bed reactor, the effluent fractionated, and the 975 "Ff [52] U S Cl 208/95, 208/108. 208/212 fraction further subjected to separation by solvent ex- [51] I clog 13/02 traction. The extract consists of gas oils, while the raf- [58] Fieid 4 4 89 97 finate, containing most of the remaining sulfur, is par- 6 3 H tially oxidized to yield hydrogen which is recycled to the hydrocracking reactor. The heavy gas oil fraction [56] References Cited from the extract may also be recycled to extinction in UNITED STATES PATENTS the hydrocracker 2,775,544 12/1956 Corneil et a1. 208/86 3 Claims, 1 Drawing Figure l l L H-OIL I AND O FEED FRACTIONATION F FURTHER I UNIT s50 975 F PROCESSING UNITS I HYDROCRKXE? & CATCRACKER H 2 I ETC.) VACUUM L BOTTOMS (RECYCLE TO H-OlL FEED) (975?) .DEASPHALII UNIT (TO SULFUR I PARTIAL RECOVERY OXIDATION DEASPHALTER BOTTOMS UNIT PROCESS FOR REDUCTION OF HIGH SULFUR RESIDUE CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION This invention relates to a process for refining hydrocarbon oils. More particularly it relates to a process for efficiently treating high sulfur, heavy hydrocarbon oils boiling above 975F.

Many of the crude oils available as energy sources contain significant amounts of sulfur. Until recently, the sulfur inclusion did not present too significant a problem. This was because after initially treating the crude oil by normal distillation and fractionation, the sulfur was for the most part concentrated in the vacuum and atmospheric bottoms or residual oils. These residual oils contained significant amounts of heavy hydrocarbons boiling higher than 975F. and were utilized by blending, until the present anti-pollution requirements restricted the use of high sulfur fuels. Various processes have been developed to refine the vacuum and atmospheric residual oils in order both to recover lighter oils and to desulfurize and otherwise upgrade the oil. One of these processes is termed the H-Oil Process and is exemplified by several issued patents, such as US. Pat. No. 3,207,688 issued Sept. 21, 1965 to Roger P. Van Driesen for a hydrocracking process. Briefly the H-Oil process is a high pressure (i.e., pressures of from 1,000 to 4,000 psi,) and high temperature (above 650F.) catalytic hydrorefining treatment utilizing an upflow reactor, solid particulate catalyst, and large volumes of hydrogen to treat a hydrocarbon oil in the liquid phase.

Regardless of the efficacy of this treatment, after removal of the treated hydrocarbons and separation into desired streams, there remains a portion which contains the sulfur compounds not removed as hydrogen sulfide or other outgases. This portion constitutes the high sulfur residue of the hydrorefining treatment, sometimes characterized as asphalts, and at present, due to stringent environmental controls, disposal of this residue as a fuel is significantly limited and poses a problem to the refinery.

SUMMARY OF THE INVENTION We have therefor invented a process for disposing of the high sulfur residues resulting from the high temperature, high pressure catalytic hydrorefining of sulfurcontaining, heavy hydrocarbon oils, in which at least 95 vol.% boils above about 975F., and obtaining essentially only low-sulfur hydrocarbon products boiling below 975F. The process comprises:

a. hydrocracking and hydrodesulfurizing said heavy hydrocarbon oil boiling above about 975F. with hydrogen in a hydrogen refining zone, at a pressure from about 1,000 psi to about 4,000 psi and a temperature of between 650F. and 950F., by passing said oil and hydrogen upwardly through a particulate catalyst bed in said zone to obtain a hydrorefined oil,

b. fractionating the hydrorefined oil, obtaining therefrom at least one residual fraction boiling above about 975F. and at least one fraction boiling below 975F.,

c. solvent deasphalting said fraction boiling above about 975F. to give a deasphalted gas oil and a raffinate and,

d. partially oxidizing said raffinate to extinction, to obtain a hydrogen stream therefrom, sufficient to meet the requirement of step (a) (or equivalent in quantity to the hydrogen used in step (a)).

BRIEF DESCRIPTION OF THE DRAWING The F IGURE, illustrates, in block diagram form, one version of the process according to the present invention. It is to be noted that the only products entering this system are the defined feedstocks and that the only products from the system, apart from H 8 by-product gas, are low-sulfur hydrocarbons boiling below 975F.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Briefly, our process contemplates incorporating a solvent deasphalting step and a partial oxidation of the resultant raffinate with the step of the severe catalytic hydrorefining of a vacuum or atmospheric residual oil containing significant amounts of sulfur. This combination of steps furnishes a satisfactory answer to the problem of high sulfur hydrocarbon residues. The term hydrorefining includes processes such as hydrocracking, hydrodesulfurization, hydrodenitrogenation, hydrodemetalization, etc.

The terms H-Oil Unit, Deasphalting Unit and Partial Oxidation Unit are well-known and used in petroleum refining. A broad description of such terms can be found in Hydrocarbon Processing, Sept., 1970 (Gulf Publishing Company, Houston, Tex.).

The following broadly describes the process diagrammatically illustrated by the FIGURE.

In the FIGURE, the hydrogen refining zone is provided by an H-Oil reactor. The H-Oil reactor is an upflow catalytic reactor containing a particulate hydrodesulfurization catalyst and maintained at a temperature of between 650F. and 950F., preferably between 750F. and 900F. Pressure can range from about 1,000 to about 4,000 psi, preferably between about 2,000 and 3,000 psi. Space velocity maintained in the reactor is sufficient to maintain the particulate catalyst in an expanded state. The quantity of hydrogen required may be between 1,000 and 50,000 cu.ft. of hydrogen per barrel of oil, but is preferably between about 5,000 and 10,000 SCFB. The parameters of the H-Oil process can be adjusted to furnish varying levels of cracking (or conversion) and desulfurization.

The feed for the H-Oil reactor is typically a heavy residuum from conventional atmospheric or vacuum fractionator bottoms. It is emphasized that the feed for the process of this invention is a heavy hydrocarbon feed which is characterized in that at least of the feed boils above about 975F. Broadly, the sulfur content of such feedstock ranges from about 1 to about l0 wt.%, preferably from about 2 to about 8 wt.%, and the metal content can range up to about 1,000 ppm. Broadly, this feed represents material which in the past had a low value and was typically blended off.

If desired, multiple H-Oil reactors can be employed, such as in a parallel arrangement. The effluents from the reactor and associated fractionators typically comprise (a) a 650F. fraction (light ends, middle distillates etc.), (b) a 650975F. gas oil fraction, and (c) 975F. heavy residual bottoms from vacuum fractionation. Fractions (a) and (b) typically go to additional processing units. Previously, the 975F. bottoms were sent to blending. An important part of this invention is that all these 975F. heavy bottoms are now processed in a deasphalting unit, and all the resultant deasphalter bottoms (raffinate) are partially oxidized to produce hydrogen for use in the l-I-Oil unit. This invention is characterized by its versatility in handling the defined feedstocks. If, for example, a high sulfur feed requires more hydrogen in the reactor, the conversion level in the reactor is adjusted (in this case, lowered) to furnish a larger amount of unconverted feed having the characteristics of asphalt. This asphalt fraction is deasphalted, furnishing more feed to the partial oxidation unit, which can thus furnish more hydrogen to the reactor. Conversely, a lower hydrogen requirement results in a higher conversion level in the reactor. This invention eliminates the heavy high-sulfur residue, in that there are not 975F. residues remaining after completion of the process. This invention contrasts with prior art processes which result in the net production ofsome 975F. residues. Essentially, the steps of the process are interdependent, in that one portion of this process depends on the other parts. Thus, a given feedstock uses a certain amount of hydrogen for a given degree of conversion, desulfurization etc. From this conversion, a certain amount of deasphalter bottoms is available and used as feed for the partial oxidation unit, which in turn furnishes the hydogen sufficient and necessary, or equivalent in quantity, for processing of the feedstock. Thus, no 975F. high sulfur residue is produced. In other words, the deasphalter and partial oxidation unit feed rates are adjusted to produce the precise hydrogen requirements needed in the H-Oil hydrocracking, hydrodesulfurization, etc. step. The deasphalter feed rate is adjusted by changing the 975"F. conversion in the H-Oil Unit. In essence, no 975F. high sulfur heavy residue, or deasphalter bottoms, remains.

The deasphalting unit includes apparatus for deasphalting, fractionation, solvent recovery, etc. The heavy bottoms feed to this unit will typically have an API gravity between about -5 and about +l and a sulfur content between about 1.5 and about 7.0 wt.%. The important effluents from this unit are (a) deasphalted gas oil and (b) deasphalter bottoms. The deasphalted gas oil stream will typically have the characteristics of from about +2 to about +1 API gravity and from about 0.5 to about 5.0 wt.% sulfur, while the deasphalter bottoms will have a gravity of from about l0 to about 2 API and from about 2.5 to about 8 wt.% sulfur. In one embodiment of this invention, the deasphalted gas oil stream is recycled to the H-Oil feed, as shown by the dotted line in the FIGURE. Previously, this stream was typically blended, but recycling now upgrades this stream by hydrocracking and hydrodesulfurization. If this system is recycled, the hydrogen requirement in the H-Oil reactor is greater than if this stream is sent to other processing units. Typical operating conditions for a solvent deasphalting unit are well known in the refining industry. The solvents used are typically C -C paraffins, with the solventzresiduum vol. ratio ranging from about 2:1 to about 10:]. The temperature can range from about l25-600F., with the pressure ranging from about 200-1 ,000 psi.

An example of partial oxidation processes suitable for use in practicing the invention is the Synthesis Gas Generation Process of Texaco. This is a continuous, non-catalytic process for the production of hydrogen by partial oxidation of gas or liquid hydrocarbons. A carefully controlled mixture of preheated fuel, in this case the deasphalter bottoms (raffinate), and oxygen is fed to the top ofa reactor. Free oxygen first reacts with fuel to produce CO water vapor and heat. A secondary exothermic reaction between the gases and additional fuel forms hydrogen and CO. In the case ofliquid fuel feed, steam is also injected to the reactor.

Effluent from the reactor is then charged to a shift converter with high-pressure steam, which is generated at no cost by utilizing the heat content of the generatoreffluent gas in a direct-quenching system or a wasteheat boiler. In the shift converter, CO is converted to CO with accompanying production of H The gaseous effluents from this unit are subjected to conventional clean-up steps, with hydrogen and H 8 being the desirable components. Typically, the effluent hydrogen stream has a purity of greater than 60 vol.%, suitable for use as the-hydrogen source for the H-Oil unit.

The combination of the above steps offers a convenient method of utilizing high-sulfur high-boiling oils, such as from petroleum, coal or other sources. The defined feedstock is known and typical. Solvent deasphalting is a convenient and well-known method of extracting gas oil from residuums. The partial oxidation step utilizes deasphalter bottoms as a source of feed, of hydrogen production and of recoverable sulfur. The hydrogen produced satisfies the requirement of the H-Oil reactor feed. The gas oil effluents can be further processed in other units. An upgrading of the highsulfur feed of the H-Oil reactor takes place and no 975F. residue results.

In practicing the invention, the operating conditions in the various units are adjusted so that the deasphalter bottoms are consumed in the partial oxidiation unit, with the concurrent production of enough hydrogen to satisfy the the needs of the H-Oil unit or additional units. Thus, the net products of the process are lowsulfur hydrocarbon streams boiling below 975F.

With a view to further illustrating the process of this invention, the following example is given.

EXAMPLE Feed Stock Inspection Boiling Range 975F.+. Vol. s 10o Gravity, Degrees API 4.8 Sulfur. W1. 7c 4.6 Metals. Vanadium Nickel, ppm 250 H-Oil Yields and Properties C. Liquid API 24.0 Sulfur, Wt. 1.] Conversion of Feed. 72 75 Fractionation of the effluent of the H-Oil reactor gives these results:

Fraction Volume 72 Sulfur. Wt. 7: BPSD 5 975F. g g A 11000 10 Chemical hydrogen consumption (S CF/bbl) I280 The vacuum bottoms from the H-Oil system, comprising ll,000 BPSD of 975F. material containing 2.6% sulfur, are subjected to deasphalting to extract 7,200 BPSD of 64 API deasphalter gas oil having a 2.1 sulfur content. The deasphalted bottoms, i.e., the raffinate, comprising 3,800 BPSD of 7.0 APl material having a 3.5% sulfur content, are introduced as feedstock to the partial oxidation unit for generation of hydrogen, which is recycled as make-up hydrogen to the H-Oil reactor system.

The above example illustrates high (75 vol.%) conversion of the feedstock to lower boiling products. Hydrogen requirements for other feedstock types boiling above 975F. may vary, thus necessitating different H-Oil conversion levels (or degree of hydrocracking). The feedrates to the downstream units, i.e., processing steps downstream of the l-l-Oil unit, will thus be adjusted to produce the desired hydrogen and eliminate any production of 975F. high sulfur residue or deasphalter bottoms in excess of that required.

Having fully described our invention and wishing to cover those modifications and variations which would be apparent to those skilled in the art without departing from either the scope or spirit thereof.

We claim:

1. A process for treating a sulfur-containing heavy hydrocarbon oil, with at least vol.% boiling above about 975F., to obtain essentially only low-sulfur hydrocarbon products boiling below 975F., said process comprising, in combination:

a. hydrocracking and hydrodesulfurizing said heavy hydrocarbon oil with hydrogen in a hydrogen refining zone, at a pressure from about 1,000 psi to about 4,000 psi and a temperature of between 650F. and 950F. by passing said oil and hydrogen upwardly through a particulate catalyst bed in said zone, thus maintaining the catalyst bed in an expanded state to obtain a hydrorefined oil;

b. fractionating the hydrorefiined oil, obtaining therefrom at least one fraction boiling above about 975F. and at least one fraction boiling below 975F.;

c. solvent deasphalting said fraction boiling above about 975F. to give a deasphalted gas oil and a raffinate;

d. partially oxidizing said raffmate to extinction, to obtain a hydrogen stream therefrom equivalent in quantity to that used in step (a), and

e. recycling the hydrogen from step (d) to step (a).

2. The process of claim 1 in which step (a) is conducted at a temperature range of about 750-900F. and a pressure range of about 2,000-3,000 psi.

3. The process of claim 1 wherein the deasphalted gas oil from step (c) is recycled, to extinction, to step 

1. A PROCESS FOR TREATING A SULFUR-CONTAINING HEAVY HYDROCARBON OIL, WITH AT LEAST 95 VOL.% BOILING ABOVE ABOUT 975*F., TO OBTAN ESSENTIALLY ONLY LOW-SULFUR HYDROCARBON PRODUCTS BOILING BELOW 975*F., SAID PROCESS COMPRISING, IN COMBINATION: A. HYDROCRACKING AND HYDRODESULFURIZING SAID HEAVY HYDROCARBON OIL WITH HYDROGEN IN A HYDROGEN REFINING ZNE, AT A PRESSURE FROM ABOUT 1,000 PSI TO ABOUT 4,000 PSI AND A TEMPERATURE OF BETWEEN 650*F. AND 950*F. BY PASSING SAID OIL AND HYDROGEN UPWARDLY THROUGH A PARTICULATE CATALYST BED IN SAID ZONE, THIS MAINTAING THE CATALYST BED IN AN EXPANDED STAT TO OBTAIN A HYDROREFINED OIL: B. FRACTIONING THE HYDROREFINED OIL, OBTAINING THEREFORM AT LEAST ONE FRACTION BOILING ABOVE ABOUT 975*F. AND AT LEAST ONE FRACTION BOILING BELOW 975*F., C. SOLVENT DEASPHALTING SAID FRACTIONBOILING ABOVE ABOUT 975*F. TO GIVE A DEESPHALTED GAS OIL AND A RAFFINATE: D. PARTIALLY OXIDIZING SAID RAFFINATE TO EXTINCTION, TO OBTAIN A HYDROGEN STREAM THEREFROM EQUIVALENT IN QUANTITY TO THAT USED IN STEP (A), AND E. RECYCLING THE HYDROGEN FROM STEP (D) TO STEP (A).
 2. The process of claim 1 in which step (a) is conducted at a temperature range of about 750*-900*F. and a pressure range of about 2,000-3,000 psi.
 3. The process of claim 1 wherein the deasphalted gas oil from step (c) is recycled, to extinction, to step (a). 